Fix nuspec description. (#12)

Author: networkfusion

nanoFramework.Azure.Devices.Client.nuspec

@@ -16,7 +16,7 @@
     <repository type="git" url="https://github.com/nanoframework/nanoFramework.Azure.Devices" commit="$commit$" />
     <copyright>Copyright (c) .NET Foundation and Contributors</copyright>
     <description>This package includes the .NET nanoFramework.Azure.Devices.Client assembly for nanoFramework C# projects.
-This is an SDK for Azure IoT Hub using MQTT boker.</description>
+This is an SDK for Azure IoT Hub using MQTT broker.</description>
     <summary>nanoFramework.Azure.Devices.Client assembly for nanoFramework C# projects</summary>
     <tags>nanoFramework C# csharp netmf netnf Microsoft.Azure.Devices nanoFramework.Azure.Devices</tags>
     <dependencies>
@@ -43,4 +43,4 @@ This is an SDK for Azure IoT Hub using MQTT boker.</description>
     <file src="assets\nf-logo.png" target="images" />
     <file src="LICENSE.md" target="" />
   </files>
-</package>
+</package>